Tolerance
Tolerance is a concept describing the lack of response of the adaptive immune system to specific stimuli; when discussing self-tolerance, the stimuli in question are the antigens of our own tissues.
Mechanisms of tolerance
Our body maintains tolerance through a variety of mechanisms, classified based on their activity as "recessive" (passive) and "dominant" (active); in addition, some tissues are protected against the immune system (the brain, testis, eyes) by special barriers.
Recessive tolerance
Recessive tolerance is achieved through a cell-intrinsic manner. It is also regarded to as central tolerance, as it occurs within the developmental organs (bone marrow for B-cells, and thymus for T-cells).
- Immature cells will modulate themselves ("receptor editing") or undergo apoptosis ("deletion") when they bind to self-antigens.
- Anergy (functional inactivation) of self-reactive cells that managed to escape the eceptor editing and apoptosis.